Spanish police are hunting a former Nazi concentration camp doctor - known as Doctor Death - believed to be hiding in northern Spain.

Aribert Heim, 91, who worked in the Mauthausen camp, is the second most wanted Nazi suspect alive.

Authorities in Catalonia province say he could be somewhere on the north eastern coast or the Balearic Islands.

A spokeswoman said Dr Heim's exact location was not known, despite Israeli reports that an arrest was imminent.

A spokeswoman for Catalonia's autonomous police, the Mossos d'Esquadra, told the BBC that an investigation was underway.

"They are looking for this person along the Catalan coast but it could be that he is Ibiza, Mallorca or Menorca," she said.

"There is an extradition order out for him and if he is found that will be carried out."

Austrian-born Dr Heim is wanted in Germany and Austria for the deaths of hundreds of inmates by lethal injection at the Buchenwald, Sachsenhausen and Mauthausen concentration camps.

Justice

The Israeli newspaper Haaretz said at the weekend that an arrest was expected soon.

Dr Heim's research included surgery without anaesthesia and injecting prisoners with gasoline, poison and lethal drugs to see how much their bodies could take before dying, the paper said.

He is listed by the Simon Wiesenthal Center as the second most wanted Nazi alive, after Adolf Eichmann's top assistant Alois Brunner.

Dr Heim had worked in Germany after the war but disappeared in 1962 prior to plans to prosecute him.

German interior ministry spokesman Rainer Lingenthal declined to comment on the investigations to capture the doctor.

But he told the Associated Press: "You can imagine that, as far as all German authorities are concerned, there is the utmost interest in one of the last big notorious criminals possibly receiving his just punishment after all."